What are coronal mass ejections and why is it important to study them?
Coronal mass ejections (CMEs) are powerful eruptions that can blow up to 10 billion tons of the sun’s atmosphere into interplanetary space. Typically, CMEs eject about one billion tons of solar particles into space and travel at about one million mph. They can create major disturbances in the interplanetary medium (the space between planets containing electromagnetic radiation, dust, gas and plasma) and trigger severe magnetic storms if they reach Earth. CME-driven shocks may also play a significant role in the acceleration of solar energetic particles, which can damage spacecraft and harm astronauts. CMEs are often associated with solar flares and prominence eruptions, but they can occur when neither is present. Despite their importance, scientists don’t fully understand the origin and evolution of CMEs, nor their structure or extent in interplanetary space. STEREO’s unique 3-D images and movies of the structure of CMEs will enable scientists to determine their fundamental nature and
